GT 550 Oil Temperature Sender

[John1957 5]

All, still restoring the GT 550 I purchased a couple of months ago.  It is operational and I absolutely love it!!!  What a mowing beast!

 

Anyway, I am trying to replace the oil temperature sender for this unit which is Toro part number 94-7619 which of course is not available from Toro anymore.

 

This sender was used in a number of the 500 series tractors so I am betting I am not the only one whom has tried to replace it with little or no luck.

 

Has anyone had success finding a surrogate replacement for this sender that also works with the gauge?  If not, any suggestions for a workaround?

 

I know the engine is not overheating as I have tested it several times during long use with an infrared thermometer (idea from the Red Square Legion) and the oil temperature is in the is in the range specified by Kohler for the engine.

 

However, as with any restore of these tractors, you want everything to work!

 

Any advice would be greatly appreciated!

 

Thanks, John

 

[oldredrider 2,553]

Check with Kohler. They may have the sending unit. A phone call might be in order. 

[John1957 5]

Oldredrider, thanks for the response!!  I did contact Kohler and actually purchased a sender from them that fit.  However, it is designed to send a signal if the oil is overheated versus sending the temperature to the gauge.  I wish I would have asked that question first instead of buying it first...live and learn I guess  !  Thanks, John

[Achto 29,294]

The temp sender sends a resistance signal to the gauge. If some one knows the resistance range of the sender then you could find one that matches. Does any one know what type of gauge is used? Is it a VDO, DATCON, or ?

[John1957 5]

Achto, I am a novice but when  researching the web I found a diagram of temperature senders and it noted a "sender ID code" is on the nut part of the sender.  There are two sets of numbers on mine.  First, 0304 and second 008.  I don't know what to do with the numbers yet but maybe someone does.  Thanks, John

[gwest_ca-(File Mod) 11,393]

As achto stated the sending unit varies the resistance to ground in the gauge sensing wire. Something you can try.

With the gauge powered with the key in the RUN position record the reading if there is any.

Now pull the wire off the sender. This simulates high resistance. The gauge should go to maximum hot or maximum cold. Record the reading.

Now ground the sender wire to a good chassis or battery ground. This simulates low resistance. The gauge should go to maximum hot or maximum cold or opposite to the above. Record the reading.

That should determine the type of sender you need.

If you don't get the above the gauge or wiring is likely at fault.

For years a disconnected wire sent the gauges to the top of the scale but have seen the opposite happen with later product.

 

You will need to know the thread type and size also. Most likely a National pipe thread

1/8" NPT .405" OD (Approx. 13/32" or +3/8")

1/4" NPT .540" OD (Approx. 35/64" or +1/2")

3/8" NPT .675" OD (Approx. 43/64" or +5/8")

1/2" NPT .840" OD (Approx. 27/32" or -7/8")

3/4" NPT 1.050" OD (Approx. 1-3/64" or -1-1/16")

 

Garry

[shallowwatersailor 3,214]

Here is a site that says no longer available but "In Stock." It might be worth a call. I haven't done business with them.

 

http://toro.partstockpile.com/index.php/94-7619.html

[shallowwatersailor 3,214]

Here is a site that says no longer available but "In Stock." It might be worth a call. I haven't done business with them.

 

http://toro.partstockpile.com/index.php/94-7619.html

[John1957 5]

Thanks all I will give it a try!